Adjustable below-the-knee prosthesis leg

ABSTRACT

An adjustable below-the-knee prosthetic leg, which is connected between a thigh and an artificial foot, comprises a controller, a connecting mechanism, a hydraulic unit, and a shell. The connecting mechanism and the hydraulic unit are pivotally connected to the controller, and the shell is pivotally connected to the hydraulic unit. The connecting mechanism extends into a hydraulic cylinder of the hydraulic unit. The hydraulic cylinder is in communication with a reserve hydraulic cylinder and a brake hydraulic cylinder of the hydraulic unit. The prosthetic leg allows a user to climb up or go down the stairs and walk on uneven ground easily without falling down.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an adjustable below-the-knee prosthetic leg, and more particularly to an adjustable below-the-knee prosthetic leg that allows a user to climb up or go down the stairs or walk on uneven ground easily without losing balance.

2. Description of the Related Art

For those who experience amputation due to serious trauma or lesion or for those having congenital limb deficiencies, through the reconstruction of a prosthetic limb, appearance and functions that are comparable to those of a common person can be attained. Especially for those who lose the leg below the knee, besides an essential artificial foot, what's most important is a below-the-knee prosthetic leg connecting the thigh and the artificial foot.

Referring to FIG. 1A or FIG. 1B, a conventional below-the-knee prosthetic leg, which is connected between a thigh 1 a and an artificial foot 2 a, generally comprises a controller 3 a, a connecting mechanism 4 a, and a knee joint body 5 a. The controller 3 a is connected to the thigh 1 a. One end of the connecting mechanism 4 a is pivotally connected to the controller 3 a, and the other end is pivotally connected to a piston structure 51 a inside the knee joint body 5 a. Furthermore, the controller 3 a is also pivotally connected to the knee joint body 5 a.

The knee joint body 5 a has a hydraulic cylinder 50 a provided therein. The piston structure 51 a is provided inside the hydraulic cylinder 50 a. The connecting mechanism 4 a is connected to the piston structure 51 a. The piston structure 51 a divides the hydraulic cylinder 50 a into an upper hydraulic compartment 52 a and a lower hydraulic compartment 53 a. In addition, a flow path 54 a is provided inside the knee joint body 5 a for connecting the upper hydraulic compartment 52 a and the lower hydraulic compartment 53 a. Thus, when the connecting mechanism 4 a drives the piston structure 51 a to move up and down, the volumes of the upper hydraulic compartment 52 a and the lower hydraulic compartment 53 a are changed. In addition, a change in the volumes of the upper hydraulic compartment 52 a and the lower hydraulic compartment 53 a may also exert an influence on the movement of the connecting mechanism, thereby further affecting the bending of the below-the-knee prosthetic leg.

Referring to FIG. 1A, when a user intends to lift the thigh 1 a to take a first step, the crus and the knee joint body 5 a droop naturally under the action of gravity. In such a case, the connecting mechanism 4 a stretches and pushes the piston structure 51 a to move downwards, the volume of the lower hydraulic compartment 53 a is compressed, and a hydraulic liquid in the lower hydraulic compartment 53 a is injected into the upper hydraulic compartment 52 a through the flow path 54 a. At this time, the artificial foot 2 a does not touch the ground, and thus is not affected by a reactive force; therefore, the knee joint body 5 a can rotate freely along with the thigh 1 a.

Referring to FIG. 1B, when the user steps on the ground with the artificial foot 2 a, the thigh 1 a applies a force for stretching so that the relative position between the thigh 1 a and the artificial foot 2 a changes from being bent to being stretched, and the connecting mechanism 4 a is bent and drives the piston structure 51 a to move upwards. In this case, the volume of the lower hydraulic compartment 53 a increases, and the volume of the upper hydraulic compartment 52 a decreases. It should be particularly noted that the center of gravity of the user is inevitably located on this foot at this time, so that the knee joint body 5 a cannot swing along with the thigh 1 a; otherwise, the user may fall down. The reactive force applied on the artificial foot 2 a by the ground contributes to this effect, because the reactive force may be transferred to the piston structure 51 a, such that the piston structure 51 a is fixed at a position until the artificial foot 2 a leaves the ground again and the gravity center of the user is moved to the other foot.

However, what is described above is the situation of walking on even ground. In the case of climbing up or going down the stairs or walking on uneven ground, it is required that the body weight can be supported before the thigh 1 a and the artificial foot 2 a are stretched in a straight line. That is, a mechanism is required through which the volumes of the hydraulic liquid in the upper hydraulic compartment 52 a and the lower hydraulic compartment 53 a remain the same when the below-the-knee prosthetic leg is bent. Otherwise, the user may lose balance and fall down. To overcome this difficulty, many advanced below-the-knee prosthetic legs get available on the market, for example, Taiwan Patent Publication No. 564742 and EU Patent Publication No. 2478875. However, the former, due to design mistakes, cannot practically fully satisfy the requirements of a user for climbing up or going down the stairs and walking on uneven ground. The latter depends on a large amount of electronic sensing devices, which increase the cost; and the electronic elements are of low reliability and are not water-proof, which fails to meet the requirements of the industry and the users for prosthetic legs.

Therefore, in response to the requirement for Improvement of the above shortcomings, the present invention which is reasonably designed and overcomes the above shortcomings is made by the inventor through intense research and application of academic principles.

SUMMARY OF THE INVENTION

The present invention mainly aims at providing an adjustable below-the-knee prosthetic leg, which allows a user to climb up or go down the stairs and walk on uneven ground without falling down due to loss of balance, and providing angles for pivotally connecting elements, thereby enabling the user to move more easily.

To achieve the objective, the present invention provides an adjustable below-the-knee prosthetic leg which is connected between a thigh and an artificial foot, comprising: a controller provided with a first pivoting portion and a second pivoting portion, where the controller is connected to the thigh; a hydraulic unit provided with a third pivoting portion, a hydraulic cylinder, a reserve hydraulic cylinder, a brake hydraulic cylinder, an adjust-initiating compartment, and a flow system, where the hydraulic unit is pivotally connected to the second pivoting portion, and the hydraulic cylinder, the reserve hydraulic cylinder, and the brake hydraulic cylinder are in communication with each other through the flow system; a connecting mechanism which is pivotally connected to the first pivoting portion and extends into the hydraulic cylinder of the hydraulic unit; and a shell which is pivotally connected to the third pivoting portion and presses against the adjust-initiating compartment, where a horizontal angle formed between the second pivoting portion and the third pivoting portion is 40 to 60 degrees, and the shell is further connected to the artificial foot.

The present invention has the following beneficial effects. The brake valve of the present invention closes the flow path inside the brake hydraulic cylinder when a user bends the thigh and the artificial foot, and transfers the user's center of gravity onto the below-the-knee prosthetic leg, so that volume of the hydraulic liquid in the hydraulic cylinder remains the same, thereby ensuring that the user will not fall down due to loss of balance. In addition, the angle formed between the second pivoting portion and the third pivoting portion allows the user to move freely like a common person.

The following detailed description and drawings relevant to the present invention may be referenced for further understanding the features and technical contents of the present invention. However, the accompanying drawings are provided merely for reference and description, and are not intended to limit the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a decomposition diagram (1) of an action of a conventional below-the-knee prosthetic leg; FIG. 1B is a decomposition diagram (2) of the action of the conventional below-the-knee prosthetic leg;

FIG. 2 is a left side view of an adjustable below-the-knee prosthetic leg according to the present invention;

FIG. 3 is an exploded view of the adjustable below-the-knee prosthetic leg according to the present invention;

FIG. 4 is a front view of the adjustable below-the-knee prosthetic leg according to the present invention;

FIG. 5 is a cross-sectional view of the adjustable below-the-knee prosthetic leg according to the present invention shown in FIG. 4 along line 5-5;

FIG. 5A is a partial enlarged view of the adjustable below-the-knee prosthetic leg according to the present invention;

FIG. 6 is a cross-sectional view of the adjustable below-the-knee prosthetic leg according to the present invention shown in FIG. 4 along line 6-6; and

FIG. 7 is a cross-sectional view of the adjustable below-the-knee prosthetic leg according to the present invention shown in FIG. 4 along line 7-7.

LIST OF MAIN REFERENCE NUMERALS

1 a Thigh

2 a Artificial foot

3 a Controller

4 a Connecting mechanism

5 a Knee joint body

-   -   50 a Cylinder     -   51 a Piston structure     -   52 a Upper hydraulic compartment     -   53 a Lower hydraulic compartment     -   54 a Flow path

A Thigh

B Artificial foot

1 Controller

-   -   11 Plate     -   12 First joining portion     -   13 Stop block         -   131 First fixing hole     -   14 First pivoting portion         -   141 First rotating shaft     -   15 Second pivoting portion         -   151 Second rotating shaft

2 Connecting mechanism

-   -   21 Connecting rod         -   211 Fourth pivoting portion         -   212 Fourth rotating shaft     -   22 Piston rod         -   221 Head end         -   222 Tail end         -   223 First piston cup         -   224 First ring         -   225 Second piston cup

3 Hydraulic unit

-   -   31 Second fixing hole         -   311 Securing screw     -   32 Hydraulic cylinder         -   321 First pressing surface         -   322 Upper hydraulic compartment         -   323 Lower hydraulic compartment     -   33 Reserve hydraulic cylinder         -   331 Third piston cup         -   332 Auxiliary elastic body         -   333 Fourth piston cup         -   334 Second ring     -   34 Brake hydraulic cylinder         -   341 First compartment             -   3411 Third ring             -   3412 Gap         -   342 Second compartment         -   3421 Fourth ring         -   343 First spring         -   344 Block valve             -   3441 First channel         -   345 Second spring         -   346 Adjusting valve             -   3461 First guiding surface             -   3462 Second guiding surface             -   3463 Second channel         -   347 Brake-initiating valve             -   3471 Stop portion             -   3472 Fifth ring         -   348 Stopper     -   35 Flow system         -   351 First flow path             -   3511 Third screw hole             -   3512 Second pressing surface             -   3513 First valve needle             -   3514 First screw not portion             -   3515 First conical surface             -   3516 Sixth ring         -   352 Second flow path             -   3521 Fourth screw hole             -   3522 Third pressing surface             -   3523 Second valve needle             -   3524 Second conical surface             -   3525 Second screw nut portion             -   3526 Fourth ring     -   36 Third pivoting portion         -   361 Third rotating shaft     -   37 Adjust-initiating compartment         -   371 Elastic element

4 Shell

-   -   41 Gap     -   42 First screw hole     -   43 First adjusting screw     -   44 Second screw hole     -   45 Second adjusting screw     -   46 Second joining portion

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 2 to 3, the present invention provides an adjustable below-the-knee prosthetic leg which is connected between a thigh A and an artificial foot B. The below-the-knee prosthetic leg comprises a controller 1, a connecting mechanism 2, a hydraulic unit 3, and a shell 4.

The controller 1 is formed by two connected plates 11, where a first joining portion 1 is provided at a junction thereof for being joined to the thigh A. A stop block 13 is sandwiched between the two plates 11. The stop block 13 has two first fixing holes 131 thereon. The two plates 11 are connected into one piece, and provided with a first pivoting portion 14 and a second pivoting portion 15, where the first pivoting portion 14 and the second pivoting portion 15 are both formed by two sets of through holes in the two plates 11.

The connecting mechanism 2 is formed by a connecting rod 21 and a piston rod 22 that are pivotally connected to each other. The first pivoting portion 14 is pivotally provided with a first rotating shaft 141, and the first rotating shaft 141 is pivoted to one end of the connecting rod 21. The other end of the connecting rod 21 is provided with a fourth pivoting portion 211 formed by two clamp blocks having a through hole, which is used for pivotally connecting to the piston rod 22.

FIG. 5 is a cross-sectional view of FIG. 4. Referring to FIGS. 3 to 5, the piston rod 22 has a head end 221 and a tail end 222, where the head end 221 has a through hole, and the head end 221 and the fourth pivoting portion 211 are pivotally connected by a fourth rotating shaft 212. Thus, when the controller 1 is applied with an external force and rotates, the controller drives the connecting mechanism 2 formed by the connecting rod 21 and the piston rod 22 to stretch or bend. The tail end 222 of the piston rod 22 extends into the hydraulic unit 3, and is sleeved with a first piston cup 223. The first piston cup 223 is a hallow cylindrical cup with an opening at one end, on which a first ring 224 is sleeved. In addition, a second piston cup 225 is further provided between the head end 221 and the first piston cup 223, where the second piston cup 225 is a hallow cylindrical cup with openings on both ends, and is movably sleeved on the piston rod 22, so that the first piston cup 223 and the second piston cup 225 may be used to cause the hydraulic liquid in each hydraulic cylinder to flow when the connecting mechanism 2 is moved.

The hydraulic unit 3 has a second rotating shaft 151 extending through two sides at a position close to the too, and has two second fixing holes 31 on a front side. The second rotating shaft 151 is pivotally connected to the second pivoting portion 15 of the controller 1, and two securing screws 311 are additionally provided to for locking the first fixing holes 131 on the controller land the second fixing holes 31. The hydraulic unit 3 is provided with several hydraulic cylinder chambers and a flow path, including a hydraulic cylinder 32, a reserve hydraulic cylinder 33, a brake hydraulic cylinder 34, and a flow system 35. The connecting mechanism 2 extends to the hydraulic cylinder 32. The hydraulic cylinder 32 has an external first pressed surface 321, and the second piston cop 225 on the piston rod 22 presses against the first pressed surface 321. Therefore, when the connecting mechanism 2 is moved, only the first piston cup 223 sleeved at and fixed to the tail end 222 may move up and down and divides the hydraulic cylinder 32 into an upper hydraulic compartment 322 and a lower hydraulic compartment 323.

Referring to FIGS. 2 and 5, when the user stretches the thigh A and transfers the center of gravity as described in the present invention, the controller 1, the hydraulic unit 3, and the shell 4 are in a stretched state, the artificial foot B steps on the ground, and the connecting mechanism 2 is bent with the pulling up by the controller 1 and the pushing by a reactive force applied on the artificial foot B by the ground. When the user lifts the thigh A and transfers the center of gravity to the other foot, the below-the-knee prosthetic leg is hung in the air and the gravity naturally acts on the artificial foot B and causes the hydraulic unit 3 and the shell 4 to move, thereby bending them relative to the controller 1. The hydraulic unit 3 may rotate about the second rotating shaft 151 and cause the connecting mechanism 2 to stretch.

When the below-the-knee prosthetic leg is stretched, the volume of the upper hydraulic compartment 322 is compressed as the connecting mechanism 2 is bent, and the volume of the lower hydraulic compartment 323 increases. When the below-the-knee prosthetic leg is bent, the volume of the upper hydraulic compartment 322 increases as the connecting mechanism 2 is stretched, and the volume of the lower hydraulic compartment 323 decreases. The first ring 224 ray fill in a gap between the first piston cup 223 and an inner wall of the hydraulic cylinder 32, thereby preventing the hydraulic liquid in the upper hydraulic compartment 322 and the lower hydraulic compartment 323 from flowing therethrough.

Referring to FIGS. 5 and 6, the flow system 35 is divided into a first flow path 351 and a second flow path 352. The upper hydraulic compartment 322 and the lower hydraulic compartment 323 are in communication with the brake hydraulic cylinder 34 through the first flow path 351 in the flow system 35, and the brake hydraulic cylinder 34 is in communication with the reserve hydraulic cylinder 33 through the first flow path 351. Therefore, by controlling the flow of the hydraulic liquid in the brake hydraulic cylinder 34, the movement of the connecting mechanism 2 may be affected, thereby producing a braking effect.

Referring to FIGS. 5 and 5A, the brake hydraulic cylinder 34 controls the flow of the hydraulic liquid between the hydraulic cylinder 32 and the reserve hydraulic cylinder 33 through an arrangement below. The brake hydraulic cylinder 34 is provided below the reserve hydraulic cylinder 33, and the hydraulic liquid that flows from the reserve hydraulic cylinder 33 through the first flow path 351 to the hydraulic cylinder 32 must pass through the brake hydraulic cylinder 34. The brake hydraulic cylinder 34 has a first compartment 341, a second compartment 342, and a first spring 343 provided therein. The first compartment 341 is provided at a position further deep into the brake hydraulic cylinder 34 than the second compartment 342. One end of the first spring 343 is connected to an inner wall of the brake hydraulic cylinder 34, and the other end presses against a block valve 344. The first spring 343 and the block valve 344 are both located in the first compartment 341. A second spring 345 and an adjusting valve 346 are located between the first compartment 341 and the second compartment 342. One end of the second spring 345 is connected to an inner wall of the second compartment 342, and the other end presses against the adjusting valve 346. The adjusting valve 346 has a first guiding surface 3461 and a second guiding surface 3462 on side surfaces. The first guiding surface 3461 matches a contact end on the block valve 344, the second guiding surface 3462 presses against a brake-initiating valve 347, and the second guiding surface 3462 matches a contact end of the brake-initiating valve 347. The other end of the brake-initiating valve 347 opposite to the contact end corresponds to a first adjusting screw 43 that is installed inside the shell 4. The brake-initiating valve 347 is located inside the second compartment 342, and has a circular stop portion 3471. A stopper 348 is positioned between the second compartment 342 and the first compartment 341. The stop portion 3471 is located inside the stopper 348. When the brake-initiating valve 347 is moved, the stopper 348 and the stop portion 3471 press against each other, thereby producing the effect of limiting the brake-initiating valve 347.

A third ring 3411 is sleeved on the first compartment 341, a fourth ring 3421 is sleeved on the second compartment 342, two fifth rings 3472 are sleeved on the brake-initiating valve 347, and the third ring 3411, the fourth ring 3421, and the fifth rings 3472 are all used to prevent the hydraulic liquid in the brake hydraulic cylinder 34 from leaking out. In addition, the hydraulic liquid flowing to the brake hydraulic cylinder 34 through the first flow path 351 flows through a first channel 3441 provided in the block valve 344, a gap 3412 between the first compartment 341 and the block valve 344, a second channel 3463 above the adjusting valve 346, and then through the first flow path 351 to the reserve hydraulic cylinder 33.

In particular, in the brake hydraulic cylinder 34, the spring force of the second spring 345 is greater than that of the first spring 343, Therefore, when the adjusting valve 346 is not pushed by the brake-initiating valve 347, the natural state of the second spring 345 may indirectly cause the first spring 343 to be in a compressed state. When the shell 4 causes the first adjusting screw 43 to push the brake-initiating valve 347, the brake-initiating valve 347 may push the adjusting valve 346 to move downwards and compress the second spring 345. In such a case, the first spring 343 starts to restore, to push the block valve 344 to move towards the adjusting valve 346, and the gap 3412 is closed. At this time, the hydraulic liquid cannot flow from the brake hydraulic cylinder 34 and between the hydraulic cylinder 32 and the reserve hydraulic cylinder 33. That is, the first flow path 351 passing through the brake hydraulic cylinder 34 is blocked, so as to keep the volumes of the upper hydraulic compartment 322 and the lower hydraulic compartment 323 of the hydraulic cylinder 32 unchanged, thereby limiting the movement of the connecting mechanism 2. A second valve needle 3523 is adjusted to control the flow rate, to achieve the braking effect. When the first adjusting screw 43 leaves the brake-initiating valve 347, the second spring 345 starts to restore, thereby pushing the brake-initiating valve 347 and the block valve 344 back to their original positions. In this case, the gap 3412 is opened again, and the first flow path 351 is unblocked.

When the first flow path 351 is not blocked by the block valve 344, if the controller 1 pushes the connecting mechanism 2 to drive the first piston cup 223 to compress the lower hydraulic compartment 323, most of the hydraulic liquid in the lower hydraulic compartment 323 may flow to the reserve hydraulic cylinder 33 through the brake hydraulic cylinder 34. The reserve hydraulic cylinder 33 has a third piston cup 331, an auxiliary elastic body 332, and a fourth piston cup 333 provided therein. The third piston cup 331 and the fourth piston cup 333 are both hallow cylindrical cups having an opening at one end, and have outer surfaces closely adjacent to the inner wall of the reserve hydraulic cylinder 33. The third piston cup 331 is sleeved at one end of the auxiliary elastic body 332, and is fixed to a top of the reserve hydraulic cylinder 33. The fourth piston cup 333 is sleeved at and fixed to the other end of the auxiliary elastic body 332, on which several second rings 334 are sleeved. The elongation and compression of the auxiliary elastic body 332 depends on the force applied to the hydraulic liquid in the reserve hydraulic cylinder 33, and the second rings 334 may be used to prevent the hydraulic liquid from penetration between the third piston cup 331 and the fourth piston cup 333. When the below-the-knee prosthetic leg is bent, to drive the connecting mechanism 2 to push the hydraulic liquid in the lower hydraulic compartment 323 into the reserve hydraulic cylinder 33, the hydraulic liquid pushes the fourth piston cup 333 to compress the auxiliary elastic body 332. However, when the external force applied on the connecting mechanism 2 decreases gradually or vanishes, the compressed auxiliary elastic body 332 restores and pushes the fourth piston cup 333 to feed the hydraulic liquid in the reserve hydraulic cylinder 33 back to the hydraulic cylinder 32, thereby causing the connecting mechanism 2 to be bent again, and thus causing the below-the-knee prosthetic leg to stretch out.

Referring to FIG. 2, the hydraulic unit 3 is provided with a third pivoting portion 36 at two sides below the second fixing holes 31. A line connecting the second pivoting portion 15 and the third pivoting portion 36 forms an angle θ with the horizontal line, where the angle θ ranges from 40 to 60 degrees. The third pivoting portion 36 is configured to be pivoted to the shell 4. A third rotating shaft 361 extends through the shell 4 at a position close to the top, and the third rotating shaft 361 is pivoted to the third pivoting portion 36. An inner edge of the shell 4 matches an outer edge of the hydraulic unit 3, and when the artificial foot B is under the action of gravity merely and the hydraulic unit 3 and the shell 4 are caused to bend and hang naturally from the controller 1, a gap 41 exists between the shell 4 and the hydraulic unit 3. When the center of gravity of the user is transferred to the thigh A, such that the shell 4 causes the first adjusting screw 43 to push the brake-initiating valve 347, and the block valve 344 closes the brake hydraulic cylinder 34, the gap 41 is accordingly closed, or decreased. A bottom of the shell 4 is provided with a second joining portion 46 for being joined to the artificial foot B.

FIG. 6 is another cross-sectional view of FIG. 4. Referring to FIGS. 4 to 6, the adjustable below-the-knee prosthetic leg according to the present invention may be adapted to users with different weights or exercises. The shell 4 has a first screw hole 42 and a second screw hole 44. The first adjusting screw 43 is screwed into the first screw hole 42. The hydraulic unit 3 has an adjust-initiating compartment 37 corresponding to the second screw hole 44 provided therein. The adjust-initiating compartment 37 is arranged in parallel to the brake hydraulic cylinder 34 and presses against the shell 4. One end of an elastic element 371 is connected to an inner side of the adjust-initiating compartment 37, where the elastic element 371 is a strong elastic body which requires a great external force for elongation or compression. Another end of the elastic element 371 presses against a second adjusting screw 45, and the second adjusting screw 45 is screwed into the second screw hole 44. In this way, the user may rotate the second adjusting screw 45 to determine the elongation and compression of the elastic element 371 and the depth of the gap 41. If the user has a heavy weight or exercises a lot, the elastic element 371 may be required to produce a higher elastic force. Similarly, when the user has a light weight or exercises little, the elastic element 371 is only required to produce a small elastic force. It should be noted that the restore of the elastic element 371 also enables the first adjusting screw 43 to stop pushing the brake-initiating valve 347, thereby opening the flow path for unblocking the first flow path 351. In addition, the restoring force provided by the second spring 345 in the brake hydraulic cylinder 34 is only sufficient for pushing the block valve 344 and the brake-initiating valve 347, and is insufficient for pushing the whole shell 4. Therefore, the shell 4 is moved by the elastic element 371 in the adjust-initiating compartment 37.

The first flow path 351 has a third screw hole 3511 extending to the outside of the hydraulic unit 3 below the hydraulic cylinder 32, and the third screw hole 3511 has a second internal pressed surface 3512 and is crewed with a first valve needle 3513 for controlling the flow rate. The first valve needle 3513 is provided with a first screw nut portion 3514, and the first screw nut portion 3514 is clamped in the second pressed surface 3512. The third screw hole 3511 has a first internal conical surface 3515, where the conical surface is located exactly at an intersection where the first flow path 351 connects the lower hydraulic compartment 323 and the brake hydraulic cylinder 34. The shape of a top of the first valve needle 3513 matches that of the first conical surface 3515, and a sixth ring 3516 is sleeved between the first screw nut portion 3514 and the second pressed surface 3512, which may prevent the hydraulic liquid from leakage out.

The invention allows the user to finely adjust the hydraulic liquid conveyed between the hydraulic cylinder 32 and the reserve hydraulic cylinder 33 independent of the braking effect produced by the first flow path 351. The second flow path 352 may be independently in communication with the hydraulic cylinder 32 and the reserve hydraulic cylinder 33, and a fourth screw hole 3521 extending outside of the hydraulic unit 3 is provided in the second flow path 352 at a position that is parallel to the third screw hole 3511, and has a third internal pressed surface 3522 and is screwed with a second valve needle 3523 for controlling the flow rate. The second valve needle 3523 has a second screw nut portion 3525, and the second screw nut portion 3325 is clamped in the third pressed surface 3522. The fourth screw hole 3321 has a second internal conical surface 3524, and the conical surface is located exactly at an intersection where the second flow path 352 connects the lower hydraulic compartment 323 and the reserve hydraulic cylinder 33. The shape of a top of the second valve needle 3523 matches that of the second conical surface 3524, and there is also a fourth ring 3526 for preventing the hydraulic liquid from leakage out. When the brake hydraulic cylinder 34 is closed, the user may control the flow rate of the hydraulic liquid by adjusting the second screw nut portion 3525, thereby affecting the braking rate.

Referring to FIG. 2, it should be noted that an angle θ formed between a line connecting the centers of the second pivoting portion 15 and the third pivoting portion 36 and the horizontal line ranges from 40 to 60 degrees, and the third pivoting portion 36 is a center of rotation of torque. When the center of gravity is transferred to the thigh A, the artificial foot B steps on the ground and receives a reactive force from the ground; when the torque produced by the reactive force is greater than the elastic force of the elastic element 371, the braking function is started. Such a range of angle is a result obtained from repeated experiments conducted by the inventor. The effect is that, from the time when the heel of the artificial foot B starts to step on the ground (where a reactive force from the ground, is applied) to the time when two thirds of the footsteps on the ground, the braking function is started. At this time the center of gravity of the user starts to be transferred to the other foot, and the elastic element 371 and the second spring 345 are required to store, thereby opening the brake-initiating valve 347 for unblocking the flow path between the hydraulic cylinder 32 and the reserve hydraulic cylinder 33. In this way, the below-the-knee prosthetic leg may swing naturally after the center of gravity is transferred. The angle set between the second pivoting portion 15 and the third pivoting portion 36 affects the movement relationship between the controller 1, the hydraulic unit 3, and the shell 4.

FIG. 7 is another cross-sectional view of FIG. 4 and shows another preferential embodiment of this creation. The major difference in structure between this embodiment and the embodiment described above lies in that no adjusting valve 346, stop portion 3471 of the brake-initiating valve 347, and stopper 348 are provided in the brake hydraulic cylinder 34, but the braking effect similar to that in the embodiment described above can still be attained.

When the shell 4 causes the first adjusting screw 43 to push the brake-initiating valve 347, the brake-initiating valve 34 may push and compress the second spring 345. In this case, the block valve 344 pressing against the brake-initiating valve 347 and provided perpendicular thereto may be pushed upwards by the first spring 343 which is in a compressed state originally, thereby closing the gap 3412 between the first channel 3441 and the block valve 344, so that the hydraulic liquid between the hydraulic cylinder 32 and the reserve hydraulic cylinder 33 cannot flow through the first flow path 351.

When the first adjusting screw 43 leaves the brake-initiating valve 347, the previously compressed second spring 345 starts to restore, thereby pushing the brake-initiating valve 347 back to its original position; and the reset brake-initiating valve 347 may press the block valve 344 to compress the first spring 343, and the block valve 344 moves downwards, to open the gap 3412 so that the hydraulic liquid may flow through the first channel 3441.

To sum up, the adjustable below-the-knee prosthetic leg according to the present invention has the following beneficial effects:

1. By setting the brake hydraulic cylinder, when the thigh and the artificial foot are bent relative to each other, the adjustable below-the-knee prosthetic leg of the present invention connected therebetween may support the center of gravity of the user, allowing the user to climb up or go down the stairs or walk on uneven ground without falling down due to loss of balance; in addition, by setting the second adjusting screw, the elastic element, and the adjust-initiating compartment, the force required by initiation of the braking function may be adjusted according to the user's requirements.

2. The angle ranging from 40 to 60 degrees between the second pivoting portion and the third pivoting portion may facilitate the user to walk more naturally and smoothly like a common person.

3. With the cooperation between the second valve needle and the flow system, in the present invention, the amount of the hydraulic liquid passing through the flow system can be finely adjusted, so that the adjustable below-the-knee prosthetic leg according to the present invention may better meet the user's requirements.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

What is claimed is:
 1. An adjustable below-the-knee prosthetic leg, connected between a thigh and an artificial foot, comprising: a controller provided with a first pivoting portion and a second pivoting portion, wherein said controller is connected to said thigh; a hydraulic unit provided with a third pivoting portion, a hydraulic cylinder, a reserve hydraulic cylinder, a brake hydraulic cylinder, an adjust-initiating compartment, and a flow system, wherein said hydraulic unit is pivotally connected to said second pivoting portion, and said hydraulic cylinder, said reserve hydraulic cylinder, and said brake hydraulic cylinder are in communication with each other through said flow system; a connecting mechanism that is pivotally connected to said first pivoting portion and extends into said hydraulic cylinder of said hydraulic unit; and a shell that is pivotally connected to said third pivoting portion and presses against said adjust-initiating compartment, wherein a horizontal angle formed between said second pivoting portion and said third pivoting portion is 40 to 60 degrees, and said shell is further connected to said artificial foot.
 2. The adjustable below-the-knee prosthetic leg of claim 1, wherein said brake hydraulic cylinder has a first spring, a second spring, and a brake-initiating valve provided therein, and said shell has a first screw hole, said first screw hole being screwed with a first adjusting screw, said first adjusting screw being corresponding in position to said brake-initiating valve.
 3. The adjustable below-the-knee prosthetic leg of claim 2, wherein said brake-initiating valve further has an adjusting valve provided therein; when said first adjusting screw pushes said brake-initiating valve, said brake-initiating valve pushes said adjusting valve, said adjusting valve compresses said second spring downwards, said first spring pushes said block valve, acid said block valve blocks a flow path; and when said first adjusting screw leaves said brake-initiating valve, said second spring starts to restore and pushes said adjusting valve, said adjusting valve pushes said block valve and said brake-initiating valve back to their original positions, and said block valve opens said flow path.
 4. The adjustable below-the-knee prosthetic leg of claim 2, wherein when said first adjusting screw pushes said brake-initiating valve, said brake-initiating valve compresses said second spring, said first spring pushes said block valve, and said block valve blocks said flow path; and when said first adjusting screw leaves said brake-initiating valve, said second spring starts to restore and pushes said block valve and said brake-initiating valve back to their original positions, and said block valve opens said flow path.
 5. The adjustable below-the-knee prosthetic leg of claim 1, wherein, an elastic element has one end connected to an inner side of said adjust-initiating compartment and the other end connected to a second adjusting screw, and said shell has a second screw hole corresponding to said adjusting-initiating compartment, said second adjusting screw being screwed into said second screw hole.
 6. The adjustable below-the-knee prosthetic leg of claim 1, wherein when said artificial foot is not bent and hangs naturally relative to said thigh without being applied with a reactive force, a gap exists between said hydraulic unit and said shell, the width of said gap being adjustable by said second adjusting screw; and when the center of gravity of a user is transferred to said thigh and said shell causes said first adjusting screw to push said brake-initiating valve, said gap is closed or decreased.
 7. The adjustable below-the-knee prosthetic leg of claim 1, wherein said connecting mechanism comprises a connecting rod and a piston rod, said piston rod having a head end and a tail end, said connecting rod having one end pivotally connected to said first pivoting portion and the other end pivotally connected to said head end.
 8. The adjustable below-the-knee prosthetic leg of claim 7, wherein said piston rod is provided with a first piston cup and a second piston cup, said first piston cup being sleeved at and fixed to said tail end, said second piston cup being movably sleeved between said head end and said first piston cap, said hydraulic cylinder having a first pressed surface, said second piston cup being clamped in said first pressed surface, said first piston cup dividing said hydraulic cylinder into an upper hydraulic compartment and a lower hydraulic compartment; and said reserve hydraulic cylinder is provided with a third piston cup, an auxiliary elastic body, and a fourth piston cup therein, said third piston cup being sleeved at one end of said auxiliary elastic body and being fixed to a top of said reserve hydraulic cylinder, said fourth piston cup being sleeved at and fixed to the other end of said auxiliary elastic body.
 9. The adjustable below-the-knee prosthetic leg of claim 1, wherein said flow system has a first flow path and a second flow path, said first flow path being in communication with said lower hydraulic compartment, said upper hydraulic compartment, said reserve hydraulic cylinder, and said brake hydraulic cylinder, said second flow path being in communication with said lower hydraulic compartment and said reserve hydraulic cylinder.
 10. The adjustable below-the-knee prosthetic leg of claim 9, wherein said first flow path has a third screw hole extending to the outside of said hydraulic unit, said third screw hole being screwed with a first valve needle and having a first internal conical surface, said first conical surface being located at an inter section where said first flow path connects said lower hydraulic compartment and said brake hydraulic cylinder, the shape of a top of said valve needle matching that of said first conical surface; and said second flow path has a fourth screw hole extending to the outside of said hydraulic unit, said fourth screw hole being screwed with a second valve needle and having a second internal conical surface, said second conical surface being located at an intersection where said second flow path connects said lower hydraulic compartment and said reserve hydraulic cylinder, the shape of a top of said second valve needle matching that of said second conical surface. 